The present invention relates to a clock distributing method for use in a logic processing apparatus, and more particularly to an effective method for distributing high speed clock signals.
In a logic processing apparatus, a master clock signal for determining timing of executing processing is important. Since not only the cycle but also the phase plays an important role, deterioration in waveform occurring during distribution of the master clock signal badly affects the processing. For this reason, multi-phase clock signals have conventionally been distributed from a master clock distributing unit to respective logic processing units. However, with increasing processing speeds, clock signal distribution has become more and more difficult, which leads to a need to take into consideration the application of an optical signal to clock signal distribution, and a variety of investigations have already been made into this technical area. A basic concept of the application of an optical signal to clock signal distribution is similar to that shown in J. W. Goodman, et al., "Optical Interconnections for VLSI Systems", Proc. of IEEE, vol. 72, No. 7, pp. 850-866, (July 1984). Particularly, FIG. 7 on page 859 may be regarded as the most basic construction.
FIG. 7 illustrates a construction of a prior art example. An optical signal from a master clock source 16 is delivered to respective logic processing units by means of fibers 13. The fibers 13 are coupled to photoelectric converters 12 where the optical signal is converted to an electric signal.
In this construction, the clock signal is directly distributed from the master clock source to the integrated circuit, however, no consideration is to provision of multi-phase clocks which are necessary for the processing. Also, other means essential to the reliability of integrated circuits, such as air tight sealing is not discussed. However, for putting the optical clock signal distribution into practice, it is necessary to distribute an optical clock signal without damaging the construction, such as air tight sealing and heat discharge, and to generate multi-phase clock signals with highly accurate phases.